JPS6415835A - Microcomputer - Google Patents
MicrocomputerInfo
- Publication number
- JPS6415835A JPS6415835A JP62172188A JP17218887A JPS6415835A JP S6415835 A JPS6415835 A JP S6415835A JP 62172188 A JP62172188 A JP 62172188A JP 17218887 A JP17218887 A JP 17218887A JP S6415835 A JPS6415835 A JP S6415835A
- Authority
- JP
- Japan
- Prior art keywords
- rom
- test
- contents
- register
- expected value
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Abstract
PURPOSE:To realize a ROM reading test effective to holding the secret just with addition of a simple test circuit, by supplying the expected value of the ROM contents into a microcomputer from outside to undergo the internal comparison and delivering only the result of the comparison. CONSTITUTION:A ROM 1 is addressed by a program counter 5 of a CPU 2 and an instruction code is fetched by an instruction register 7. Then the instruction code is decoded and the data on the ROM 1, a data memory 16, a port 8, etc., are successively processed by the CPU 2 including an ALU 11. When a ROM test external terminal 3 is activated, a reading test mode of the ROM 1 is set by a test control signal 4 and a control circuit 6. The increment result of the ROM addresses is latched by a register 12 via the counter 5 and at the same time the expected value of the ROM 1 is latched by a register 13. The ALU 11 performs the subtraction of contents of both registers 12 and 13 and the result of this subtraction is delivered outside via a port 14. This operation is repeated and bit '1' is delivered if the ROM contents are not coincident with the expected value of the ROM.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP62172188A JPH0646387B2 (en) | 1987-07-10 | 1987-07-10 | Micro computer |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP62172188A JPH0646387B2 (en) | 1987-07-10 | 1987-07-10 | Micro computer |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS6415835A true JPS6415835A (en) | 1989-01-19 |
JPH0646387B2 JPH0646387B2 (en) | 1994-06-15 |
Family
ID=15937208
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP62172188A Expired - Lifetime JPH0646387B2 (en) | 1987-07-10 | 1987-07-10 | Micro computer |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH0646387B2 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0701210A2 (en) | 1994-09-12 | 1996-03-13 | Nec Corporation | Data processor having data bus and instruction fetch bus provided separately from each other |
US6393520B2 (en) | 1997-04-17 | 2002-05-21 | Matsushita Electric Industrial Co., Ltd. | Data processor and data processing system with internal memories |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5717063A (en) * | 1980-07-04 | 1982-01-28 | Mitsubishi Electric Corp | Test circuit of microcomputer |
JPS5851369A (en) * | 1981-09-24 | 1983-03-26 | Nec Corp | Microcomputer with test circuit |
JPS6167168A (en) * | 1984-09-10 | 1986-04-07 | Nec Corp | Microcomputer |
-
1987
- 1987-07-10 JP JP62172188A patent/JPH0646387B2/en not_active Expired - Lifetime
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5717063A (en) * | 1980-07-04 | 1982-01-28 | Mitsubishi Electric Corp | Test circuit of microcomputer |
JPS5851369A (en) * | 1981-09-24 | 1983-03-26 | Nec Corp | Microcomputer with test circuit |
JPS6167168A (en) * | 1984-09-10 | 1986-04-07 | Nec Corp | Microcomputer |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0701210A2 (en) | 1994-09-12 | 1996-03-13 | Nec Corporation | Data processor having data bus and instruction fetch bus provided separately from each other |
EP0701210A3 (en) * | 1994-09-12 | 1996-09-04 | Nec Corp | Data processor having data bus and instruction fetch bus provided separately from each other |
US5706423A (en) * | 1994-09-12 | 1998-01-06 | Nec Corporation | Data processor having data bus and instruction fetch bus provided separately from each other |
US5958074A (en) * | 1994-09-12 | 1999-09-28 | Nec Corporation | Data processor having data bus and instruction fetch bus provided separately from each other |
US6393520B2 (en) | 1997-04-17 | 2002-05-21 | Matsushita Electric Industrial Co., Ltd. | Data processor and data processing system with internal memories |
Also Published As
Publication number | Publication date |
---|---|
JPH0646387B2 (en) | 1994-06-15 |
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